Simultaneous 100% PLQY of Mn²⁺ emission and high Pb substitution via Sr²⁺ doping in Mn-CsPbCl₃ nanocrystals

Doping Mn²⁺ ions into all-inorganic cesium lead halide perovskite nanocrystals (PNCs) offers a unique pathway for inducing a new emission channel and reducing lead toxicity. However, concentration quenching at high Mn²⁺ levels degrades the photoluminescence quantum yield (PLQY), posing a formidable challenge for reconciling a high Pb substitution rate with a high Mn²⁺ emission PLQY. In this study, we report an efficient approach for simultaneously achieving 100% PLQY of Mn²⁺ emission and an 18.58% Pb substitution rate in Mn²⁺/Sr²⁺ co-doped CsPbCl₃ NCs.This balance between a high PLQY and a high Pb substitution rate is realized by reducing defect density and mitigating lattice distortion through Sr²⁺ doping, thus enhancing energy transfer efficiency from excitons to Mn²⁺ (70.85% vs. 87.88%) and alleviating the microstrain induced by lattice distortion to facilitate the occupation of Pb²⁺ sites. The stability-enhanced Mn/Sr-CsPbCl₃@PMMA nanocrystal-polymer composite film was further fabricated for the construction of a white light-emitting diode (WLED), which achieved desirable white-light coordinates (0.338, 0.346). This work not only enriches the understanding of the luminescence properties of Mn²⁺-doped PNCs but also provides new insights for developing low-toxicity light-emitting devices.